churchill



(Model.) 2 Sheets-Sheet 1.

J. D. CHURCHILL.

SAFETY VALVBABPARATUS FOR STEAM BOILERS.

No. 256,883. Patented Apr.25,1882

Winesses' fizwniiw Q model. 2 Sheets-Sheet 2.

J. D. CHURCHILL.

SAFETY VALVE APPARATUS FOR STEAM BOILERS.

No. 256,883. Patented Apr. 25, 1882.

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'- U ITED -ST TEs PATENT OFFICE. 1

JAMES DIXON CH URGHILL, OF UPPER HOLLOWA Y, COUNTY OF MIDDLESEX,

- ENGLAND.

5 SAFETY-VALVE APPARATUS FOR STEAM-BOILERS.

SPECIFICATION forming part of Letters Patent No. 256,853, dated April 25, 1882.

i Application filed February 14, 1881. (Model.) Patented in England Julyl, 1880.

tus for Steam' Boil'ers, (for which I have ob-- tained a .patent in Great Britain, No. 2,693,

hearing date July 1, 1880,) of which the following is a specification.

My invention consists in controlling the safety-valve of a steam-boiler by steam-press- V ure acting on a piston connected to the safety- 1 valve and workingin a cylinder, the distribution of steam to which is effected in such mannerthat so long as the pressure in the boiler doesnot exceed the maximum for which the apparatus is set the steam-pressure against the piston will be on that side tending to keep the safety-valve shut; but on the said maximum pressure in the boiler being exceeded steam will be allowed to escape from that side of the piston against which it has been acting,

thus relieving the safety-valve of its load and allowing it to open; and should it stick or not open suliiciently steam will be admitted to so act on the piston as to cause opening of the safety-valve, (subsequent arrestation of the 0 piston being effected by the closing of the steam-supply and exhaust ports,) the amount of movement of the piston being regulated by the varying pressure of steam in the'boiler, and

a fall in that pressure below the, maximum for which the apparatus is set readmitting steam to act on such side of the piston as to reclose the safetyvalve.

Referring to the accompanying sheets of drawings, Figure 1 is an elevation, partly in section, of so much of a'safety-valve apparatus as is necessary to an understanding of my invention. Fig. 2 is a plan. Fig. 3 is a section in line 1 2 of Fig. 1.

to is a cylinder in communication by b with the boiler. This cylinder is truly bored from c to da distance corresponding to the depth of its contained piston e, which is provided with packing-rings at f. This piston is loaded by a spring, g, interposed between the piston and a cross-head, h, adjustable by turning the ing the fulcrump of the lever on iss'upported the cylinder t.

. '55 n p is a pin serving as fulcra to the levers m o. This pin is fixed in an arm or lever, 0, l

the partn being eccentric to the fulcrum p of ,I 7

this lever. (See Fig. 3.) The pivot constitutf in a bearing-piece, q, fixed on the right-hand f rod j. The arm mot' the lever m is connected by rod 2' to a D-slide in the steam-chest is of The ports are arranged as follows: The top 535 one communicates with the bottom of the interior of the cylinder, thenext lower port com- 1 municateswith the exhaust, and the third or: lowest communicates with the top of the interior of the cylinder.

In Fig. 1 I have supposed the piston in 'cylindent to be at the bottom of the cylinder, (which is the normal position,) with the fullf boiler-pressure above it, the port'communicating with the top of the cylinder being open to the steam-supply, while the port communieating with the bottom of the cylinder is open toythe exhaust. In'this position the safetyvalve (which is not shown, but of which n, is the lever, and "which is jointed at 'v to the pis- 8o ton-rod 20) is supposed to be closed,and the piston e in the cylinder at is in its lowest posij tion. Assuming, now, that the pressure in the boiler rises above the maximum for which the apparatus has been set by the nuts i,-th,e piston 6 will be raised in the cylindera against the resistance of the spring g, thereby tilting the lever on on its fulcrum n and moving the slide in the steam-chest s of the cylinder 2. This movement of the slide will, to begin with, close communication between the port leading to the bottom of the cylinder and the exhaust, and also will shut off steam from the port leading to the top of the cylinder. Then it will begin to open to the exhaust the port 5 leading to the top of the cylinder, thereby redncing the pressure on the top of the piston in the cylinder t, whereby the safety-valve lever is held down, thus permitting the safetyvalve to rise by the pressure of the steam [60 obtained not suffice to relieve the boiler of the excess of pressure, the continued downward movement of the D-valve will admit steam to the bottom of the cylinder it below the piston therein, thereby bringing it into operation for assisting the opening of the safety-valve. As the piston in cylinder 13 rises it, by means-of the rod to and the arm or lever o, raises the fulcrum a and lever m, thereby returning the slide in valve-chest s sufliciently to close the top and bottom ports to both steam and exhaust, thus retaining the piston iirthe position it has assumed in cylinder t. When the steam-pressure in the boiler is sufficiently lowered the piston e in cylinder a, returns to its normal position, (see Fig. 1,) and in so doing operates the slide in the valve-chest s, so as to partially open the top port to the exhaust and the bottom port to the steam, thus admitting steam above the piston in cylinder t and returning that piston to the bottom of the cylinder, thereby closing the safety-valve. As the piston descends in its cylinder 15 and closes the safety-valve the slide in the steam-chest s is returned to its normal position by the movement of the arm or lever 0, carrying the fulcrnm-pin n.

Itwill be evident that in practice the details of arrangement may be varied without departing from the essential peculiarities of my invention. Thus the rod it, instead of being attachcd-to a piston, 6, working in the cylinder a, may be connected to one of. two flexible disks, constructed of metal-such, for example, as German silver-which will not oxidize, the disk to which said rod is connected being loaded by a spring-such as g-and the load being adjustable bymeans of the cross-head and nuts, such as and e. In such a modification the two disks may be secured together by three rings, which nip the edges of the disks, so as to form a steam-tight chamber. It is to be understood that in this case steam from the boiler will enter between the disks, and when the pressure exceeds that for which the apparatus has been set the rod 70 willbe raised in opposition to the spring g, and theapparatus will operate in a similar manner tothat already described with reference to the drawings.

In place of a pair of disks, as just described, a single disk may be employed, this disk being mounted so as to form the flexible side of a chamber within which the steam-pressure acts; or two or more pairs of disks, forming chambers the interiors of which communicate, may be used.

What I claim is- 1. In safety-valve apparatus for steam-boilers wherein the safety-valve is connected to and controlled bya piston working in a cylinder, admission and emission of actuating-fluid to and from which are regulated by a slide or valve, the combination, with such slide or valve, of a piston or its equivalent in direct communication with the interior of the boiler, said piston or its equivalent being loadedby an adjustable spring adjusted by the nuts i i, or their equivalents, and connected to said slide or valve, substantially as herein specified.

2. In safety-valve apparatus for steam-boilers wherein the safety-valve is connected to and controlled by a piston Working in a cylinder, admission and emission of actuating-fluid to and from which are regulated by a slide or valve operated-through a lever, m m, by a piston or its equivalent actuated by the pressure in the boiler, the combination, with said lever m m, of an arm or lever, 0, and a pin or projection, 12, fixed to said arm or lever 0 in a position eccentric to its own fulcrum, said pin or projection 12 serving as the fulcrum ot' the lever m m, substantially as hereinbefore described, and for thepurposes specified.

3. In a safety-valve apparatus for steamboilers, the combination of a cylinder, t, containing a piston whose rod 20 is connected to the lever a of the safety-valve, a slide or valve working in steam-chest s, a rod, '1", a lever, m m, to which said rod 1" is connected, an arm or lever, 0, connected to piston-rod w, an eccentric fulcrum pin or projection, 12, on which said lever on m is mounted, a rod, 70, connected to said lever m m, and a piston, 6, working in a cylinder, a, and loaded by a spring, g, adjustable by a cross-head, h, nuts '6, and rodsj, all substantially as and for the purposes hereinbef'ore described.

JAMES DIXON CHURCHILL.

Witnesses J. SPIERS BAKER,

Notary Public, Liverpool. HY. THOMPSON, SAML. OORFE, Solicitors Olerlrs, bOl/L of 54 Castle Street, Liverpool. 

